The present invention relates to cutlery sharpening machines and more particularly to counter top mounted cutlery sharpening machines wherein the tool carrier is reciprocated by the hand of the user and is mounted in a swinging carrier. Furthermore, the machines in consideration employ a tool of an abrading nature.
The prior art for this invention is replete with methods of clamping the work during the abrading process. However, the geometry of this type of sharpener dictates that the tool carrier reciprocate in very nearly a straight line; otherwise the angle of abrasion will vary significantly. For these prior art machines to provide a consistent edge, the operator needs to constantly work the clamping mechanism open and closed as the work is progressed under the tool. This rapidly becomes tedious.
Prior art machines have been provided with means to adjust the height of the tool guide post to offer the operator a range of angle settings. The proper edge angle for a given piece of cutlery is a function of many factors: the material to be cut and the surface the edge must work against, among other considerations. Once the proper angle has been established and an initial quality edge has been formed, it is important that subsequent resharpening be done at the same angle.
The guide post of a typical machine is graduated for referencing this angle. For such a reference mark to be constant and absolute, geometry dictates that the edge of any blade, regardless of blade width, lie along an indicated reference line that is a fixed distance from the base of the guide post. Machines of the prior art have no clear indication of this reference line. Furthermore, the clamping structure employed in known machines will not accept a wide blade, such a meat cleaver, without the edge protruding far beyond the line used for angle referencing. This renders such a reference mark useless.
A further deficiency apparent in the prior art is characterized by the abrupt ends of the abrasive surface as it is presented to the work. Operators of these machines are inclined to work the abrading surface mostly in the middle to avoid these edges. This soon results in a concave stone face and consequent irregular sharpening angle. These machines will require stone replacement long before a machine conducive to full, even use of the abrading surface.